Car Engine Sensors and their Symptoms of Failure

Engine Sensors

Suzuki Liana Engine Sensors

Engine sensors on almost all modern cars work on the same principle. In this blog ‘Sensors functions’ and ‘Symptoms of failure’ will remain equally applicable to all car-makes, however, locations of sensors is mentioned for Suzuki Liana engine (M13a) in particular. Nonetheless, the sensor locations on other cars are also at similar locations / components as mentioned in this article.

Suzuki Liana is a modern age car with relatively more electronics-intense engine system as compared to cars of its category and era (2001-07). Suzuki Liana is equipped with new generation M-series engine with model numbers of M13a and M16a for 1.3L and 1.6L, respectively. Engine specifications make Suzuki Liana a highly fuel efficient and smoother car to drive.

I’ve come in contact with many people, who are unaware of the sensing mechanisms of Suzuki Liana, hence get carried away in the hands of car mechanics. I therefore decided to write this blog to give an overview to readers about Sensors installed on Suzuki Liana engine. I’ll try to cover the ‘function’, ‘location’ and ‘failure symptom’ of each sensor.

Ok let’s discuss the Sensors one by one:-

Inlet Air Temperature Sensor (IAT)

Throttle Position Sensor (TPS)

Manifold Absolute Pressure Sensor (MAP)

Engine Coolant Temperature Sensor (ECT)

Crankshaft Position Sensor (CKP)

Lambda Sensor / Oxygen Sensor (O2 Sensor)




Inlet Air Temperature Sensor (IAT)

Function:

As the name shows, the function of IAT is to sense the temperature of air entering into the engine. This temperature signal is sent to engine Electronic Control Unit (ECU) which in turn corrects the fuel injection timing accordingly.  In winter season, IAT senses lower temperatures, hence, the ECU slightly increases the fuel injection time and keeps the engine RPMs relatively higher until engine is properly warmed up.

Location:

IAT is installed on Air Cleaner box. It is push fit and stays in place with the help of rubber pad.

Symptoms of Failure:

  • Engine Maintenance Light comes ON
  • Engine RPM low or high
  • RPM dips under load (e.g when initiating wheels roll)
  • Engine stalls etc

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Throttle Position Sensor (TPS)

Function:

TPS senses two parameters, the throttle (accelerator) pedal position  and the rate of pressing / releasing accelerator i.e how fast the accelerator has been pressed or released. In modern cars, this information is required by ECU for manipulating fuel injection timings for instantaneous response to variation of throttle position.

Location:

TPS is installed on throttle body with two screws.

Symptoms of Failure:

  • At times momentary flashing of engine maintenance light during accelerator movement for no apparent reason
  • Non-responsive accelerator
  • Power surges during constant speed drive
  • Engine misfire or RPM drop at a specific throttle (accelerator) position during acceleration or deceleration
  • Momentary dip in RPM during idling

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Manifold Absolute Pressure Sensor (MAP)

Function:

There are two different sensors used in modern vehicles for measuring amount of air entering the engine, one is MAP (Manifold Absolute Pressure) sensor and the other is MAF (Mass Air Flow) sensor. Though the purpose of both sensor is same but their working principles are entirely different and can not be used interchangeably. MAP senses the pressure while the MAF senses the Mass flow rate.

Suzuki Liana is installed with MAP sensor. MAP sensor is used to measure the amount of air entering into the engine for making mixture with fuel for combustion. MAP sensor senses the absolute air pressure in the inlet duct (big black pipe directing air from air cleaner to throttle body and then to the inlet manifold), and sends this information to Electronic Control Unit (ECU) in the form of electrical signal. ECU, which is also getting inlet air temperature information through IAT sensor, calculates the air mass flow (amount of air) on the basis of these two information. Once the amount of air is known, the ECU gives signal to injectors for providing correct amount of fuel in order to have best air-fuel mixture for optimum combustion. On the basis of MAP and  IAT information, the ECU keeps correcting the fuel injection timing to keep the drive most fuel efficient.

Location:

MAP is installed on throttle body, downstream (after) of the throttle body butterfly. MAP sensor is installed with two Allen-key screws.

Symptoms of Failure:

  • Low mileage per liter due to inaccurate fuel injection timing
  • Engine throttle at times become non-responsive due to fuel overflow condition (rich mixture)
  • Smell of un-burnt fuel from engine exhaust gases
  • Engine misfire due to lean mixture
  • Rough idle RPM
  • Engine knocking under load condition
  • Hesitation during acceleration or at beginning of wheels roll

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Engine Coolant Temperature Sensor (ECT)

Function:

Engine Coolant Temperature (ECT) sensor is generally known as water temperature sensor and is considered the most important sensor and is often considered as a “Master” sensor. As we all know that coolant (water) circulates around the engine to keep it cool against the heat effects caused by combustion in engine cylinders. Like all other sensors it also generates an electrical signal as soon as the coolant temperature varies. This electrical signal from Coolant Temperature sensor does three functions:-

  1. Shows temperature indication for the driver.
  2. Electrical signal goes to ECU for adjustment of fuel. At low coolant temperatures, RPM remains higher than normal till the time engine reaches at normal operating temperatures.
  3. Gives signal to Radiator fan for automatic ON / OFF as per the requirement.

Location:

ECT is installed on a metallic housing installed on the left-side of the engine (when viewing forward from inside) . At this location, water is coming out of the engine after absorbing engine heat which is sensed by ECT sensor and requisite functions are performed. ECT is threaded on to the metallic housing.

Symptoms of Failure:

  • Faulty ECT will show inaccurate temperature on the gauge.
  • Failed ECT will indicate lower (or minimum) temperature on gauge.
  • High engine idle RPMs.
  • Smell of un-burnt fuel from engine exhaust gases due to excessive fuel supply by ECU which senses engine as cold whereas physically engine is warm.
  • Engine heats up due to inoperative radiator fan (sensing engine as cold).
  • Engine knocking due to over-temp condition.

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Crankshaft Position Sensor (CKP)

Function:

In older cars crankshaft rotation (generally known as engine timing) was manually adjusted with the help of distributors, whereas now in modern cars installed with electronic control units, the function of distributor is now being performed by Crankshaft Position Sensor (CKP). As the name shows, the Crankshaft position sensor senses the rotational speed of crankshaft and sends and electrical signal to ECU, which in response, adjusts the ‘spark-firing’ and ‘fuel injection’ timings to get optimal performance of engine, especially during starting cycle.

Location:

CKP is installed on the engine block in the surroundings of timing chain mechanism so that movement of crankshaft is sensed. CKP is threaded to the engine block housing.

Symptoms of Failure:

  • Problematic starting or delayed ignition
  • Unstable Idle RPM with engine shaking
  • Unexpected engine stalls
  • Unable to maintain constant speed during highway drive
  • Hesitation to accelerate or Jerky acceleration
  • At higher accelerator settings, Engine misfiring, backfiring or high vibrations
  • Unable to start when engine is hot, however starts when engine is cooled down after some time

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Lambda Sensor / Oxygen Sensor (O2 Sensor)

Function:

There are three names of the same sensor which are used interchangeably, but generally known as O2 Sensor. The function of this sensor is to sense the concentration of oxygen contents in the exhaust gases. If the O2 concentration is high that means engine is running on lean mixture (means more air contents) and if the O2 contents are low then the mixture is considered rich. This sensor generates an electrical signal and sends it to the ECU which adjusts the fuel injection timings and also opens the Exhaust Gas Regulator (EGR) for recycling of exhaust gases back into the intake manifold. Hence, O2 sensor ensures optimal fuel consumption by the engine. Automobiles installed with Catalytic Converter (CAT), there are TWO Lambda sensors installed, one just after the Exhaust manifold at the beginning of exhaust pipe while the other one after the CAT. First O2 sensor analyses the combustion efficiency of engine while the other one analyses the effectivity of Catalytic Converter. ECU utilizes signals of both sensors for fuel correction in order to give optimal fuel efficiency.

Location:

For automobiles with CAT, two O2 sensors are installed, one before the CAT and other one after the CAT. Whereas, only one O2 sensor is installed on automobiles without CAT which is located  at the beginning of exhaust pipe (silencer).

Symptoms of Failure:

  • High fuel consumption
  • Smell (usually like rotten egg) from exhaust gases when engine is cold
  • Unstable Idle RPM or Unexpected engine stalls
  • Unable to maintain constant speed during highway drive
  • Hesitation to accelerate

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29 comments on “Car Engine Sensors and their Symptoms of Failure”

  1. Gull Reply

    My liana’s Throttle body accelerator nob rod which connected to tiki of throttle body is leak. Seal is leak and thete is vaccum leak from that seal . do you know any solution to repair this leak ?

  2. Gull Reply

    on throttle body of liana thre are 2 sensors on is tps sensor and what is the name of other sensor which also give race to ac when we turn on ac ? what is the name of second sensor ?

    • Suzuki Liana Pk

      The other sensor on the throttle body is MAP sensor (Manifold Absolute Pressure sensor). But MAP sensor has nothing to do with the operation of AC. ECM automatically senses the load and increase the RPMs accordingly.

  3. Gull Reply

    hi, your site is very informative. i want to register but there is problem in your website or server.first on registration your site says this user name already exists then change user name, then on 2nd or 3rd attempt it says this email address is already in use. then i close the reg page.
    tell me how my email address is in use of some one else. ??
    plz solve-your site problem.

    1
  4. Rizwan Reply

    I have a liana model 2010 I have changed CNG kit with advancer but problem is that when I switch to CNG the engine light blink and in 2nd gear the accelator goes down

  5. Abdul samad Reply

    can any one tell me or refer me a best or good mechenic for my liana in which mechenic resolve the problem of jerking rpm up down problem and missing problem in ff cng. can any one refer me a machenic? plz sahre the location and contact no?

    • Suzuki Liana Pk

      Jerking on FF CNG is a common issue with Suzuki Liana due to low quality CNG. This problem generally surfaces after 75k km on odo. It is recommended to get the CNG cleaned and replace two parts of the kit i.e the diaphragm and the filter, hopefully you’ll be good to go for another 100,000 Kms. You may watch the following video to get an idea of the items:
      Landi Renzo Omegas LPG/CNG Kit Cleaning

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    1
  7. Adil Reply

    Hello..i have suzuki liana….i have error of check light on and code is pd sensor.can u tll me plz what is pd sensor and where it will be located…..

    • Suzuki Liana Pk

      I’d request you to start a topic in forum section so that community may also guide you, and discussion will also be helpful for future readers. Thanks

  8. Moosa Hassan Reply

    Dear Brother. Thank u for making such a great website. Much appreciated. I’ve selected an engine swapped liana (with original m13a liana engine), all sensors are new. I came across many liana’s, but most have issues, small and big alike. I hope with your and communities help my experience with liana is going to be alright.

    Please tell me Steering pump gives sound is steering is moved while car standing still. If this needs to be changed how much cost it gonna cost?

    2
    • Suzuki Liana Pk

      Thanks for the appreciation bro, just remember in prayers.
      Regarding steering system, firstly I’d say that operating power steering in static position is not recommended, secondly there is always some noise when steering is operated which is just normal. If you think the noise is abnormal, first get it checked from a specialist sometimes after market hoses (pressure lines) often produce some extra noise due to smaller inner diameter of the pipes. Regarding cost of repair not very sure but should not exceed PKR 5k-7k.

  9. bilal hussain Reply

    kindly tell that knock code sensor position on suzuki laina m13a engine with any picture and its work i have getting code on odb

  10. Advance Auto P Reply

    In the countless years we have been in the used car parts Melbourne industry, we were given the opportunity to witness how the cars before have truly changed and improved into more efficient, more economical, and more intelligent vehicles than ever.

    1
  11. Leonelle Reply

    Thanks for your help. I’ve already replaced the MAP sensor. It seemed to help with my acceleration surging problems. However it didnt help with the rough idle. I still experience eventual cut outs when waiting on stop lights or traffic. I’ve had the engine airways cleaned and sparks changed. MY Mechanic insists on changing the engine coils but I have no trouble starting it up nor does then engine flash. I am at my wits end. I don’t know what else to look into. Hope you can help with this. Thanks.

    Leonelle

    1
    • Suzuki Liana Pk

      To me it appears as if voltage drops intermittently, I’d recommend following checks (step wise)….
      1. Check battery terminals for any salt deposits.
      2. Loose earthing connection with car body.
      3. Loose or contaminated Fuse/relay terminals in junction box under the hood.
      4. Clean ECU connector with contact cleaner spray.
      Also perform following actions….
      5. Hopefully filters (Air/Fuel) were replaced as per the frequency.
      6. Check free rotation of Idle Air Control (IAC) valve, installed on Throttle body.
      7. Cleaning of Exhaust Gas Regulator (EGR), EGR often gets clogged due to carbon deposits.
      All above checks do not require any replacements, just cleaning and inspection. If the problem persists then, i’d recommend resistance check of Spark Plug Leads and Ignition Coils prior to replacement of either of them.

      I’d also recommend starting a topic in forum so that i may shift this discussion there for the benefit of other readers

      1
  12. Leonelle Reply

    Hi,
    Thank you so much for this very informative blog. I have a Suzuki Liana 2001 1.6 engine and it already has accumulated over 180,000kms. I’m experiencing the jerking problems on idle and difficulty in acceleration. It displays all the symptoms that relates to the MAP Sensor. However, I have difficulty locating it. Would you mind sending me a specific diagram for this area, if you have one.

    Thank you.

    1
    • Suzuki Liana Pk

      Thanks Leonelle for appreciating the blog,
      You can find the location of MAP sensor in the following diagram published in the forum section of this website, link is
      http://suzukilianapk.com/forum/?view=thread&id=11
      The location is on throttle body, generally black in color installed with two Allen-key screws. If you still dont find it let me know i’ll try to upload a real pic.

    • Waqas Akram

      dear brother thanks for sharing very use full info to maintain car easy,
      dear i face issue with my liana 2010 when i start , it cant pick salf (mean not going to starting).
      after the gape of some time when i try again its start immediately with out any time delay..
      secondly when i switch on before going to start all indications shows normally on meter, battery indication also..

      so can you give me some checks about that issue with your experience to solve the issue,
      M.waqas
      0305-1239011

    • Suzuki Liana Pk

      Bro, I’d appreciate if you start a topic in relevant forum, it will also benefit future readers.
      By the way doesn’t seems to be a big issue with your car, will suggest some measures in the forum. Moreover, other readers will also guide you with their valuable feedbacks.
      Hope you understand

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